[LLVMdev] [llvm-commits] [PATCH] A "very verbose" mode for FileCheck

Evgeniy Stepanov eugeni.stepanov at gmail.com
Wed Jan 16 15:23:51 PST 2013

On Thu, Jan 17, 2013 at 1:19 AM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
> On Wed, Jan 16, 2013 at 9:33 PM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
>> On Wed, Jan 16, 2013 at 9:24 PM, Chris Lattner <clattner at apple.com> wrote:
>>> On Jan 16, 2013, at 10:32 AM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
>>>> Hello,
>>>> When someone breaks a FileCheck-based test on some buildbot, sometimes
>>>> it may not be obvious *why* did it fail.  If the failure can not be
>>>> reproduced locally, it can be very hard to fix.
>>>> I propose adding a "very verbose" mode to FileCheck.  In this mode
>>>> FileCheck will dump the input file in case of failure.  This mode will
>>>> be enabled by an environment variable "FILECHECK_VERY_VERBOSE".  If we
>>>> chose a command line option, we would have to edit all FileCheck-based
>>>> tests to use %FileCheck.
>>> I think that this idea is good, but I'd prefer it be implemented a different way:
>>>  - Filecheck should take a new flag -dump-input-on-error that causes it to... dump the input file on error.
>>>  - Lit should be the thing that checks the environment (or perhaps add a new option to lit), and adds the flag to FileCheck invocations.
>>> I don't like it when the behavior of such a low-level tool like this changes based on environment variables.  It isn't discoverable in --help.  If for some reason, it is bad for lit to implicitly pass the option, I'd rather have a standard FILECHECK_COMMANDLINE environment variable, and have filecheck parse arbitrary options out of it using the cl::ParseEnvironmentOptions function.
>> I agree that a command line option would be better.  But in that case
>> all tests should be updated.  It is not an issue for me -- it is
>> mostly mechanical.  So should I change tests to use %FileCheck?
> Here's a third attempt.
> The new behavior is as follows:
> 1. In case of errors we always dump output to a temporary file and print

Does it mean we get one more file in /tmp every time a test fails, and
it is not cleaned up automatically? I don't think this should happen
in the "default" mode of the tool.

Other than that, the idea sounds awesome, and I'd be happy to see any
variation of it on the bots ASAP.

> Saving input file "<stdin>" to "/tmp/filecheck.txt-Jno73y"
> 2. If --dump-input-on-error option is passed, FileCheck will also dump
> input to stderr.
> 3. If FILECHECK_DUMP_INPUT_ON_ERROR env var is set, lit will replace
> "%FileCheck" with "FileCheck --dump-input-on-error".
> I will fix all tests in LLVM and Clang if we decide this is the way to go.
> Dmitri
> --
> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/
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